The invention relates to a lost mold for production of a cylinder liner or of other cast parts, especially ring carriers for pistons, and to a corresponding production method as well as to cylinder liners produced with inventive lost molds and to a composite of a plurality of cylinder liners and other cast parts.
The production of cylinder liners with lost molds is known in itself from, for example, German Patent (DE) 3909521 A. The production of what are known as rough cast liners from cast iron is also known. In the process the rough surface provided with undercuts is made by a special slip.
A corresponding method for aluminum liners is not yet known.
The invention therefore deals with the problem of providing a method and a corresponding lost mold for production of a cast liner, especially of aluminum, having a rough outside surface.
This problem is solved by a lost mold according to the invention. Advantageous improvements are discussed below.
The inner core of this lost mold and the particles can be made, for example, from polystyrene. Of course, all other materials that are suitable for lost molds can also be considered.
By virtue of the structured surface of the lost mold formed from particles, a rough surface with undercuts is obtained during casting of the liner. During subsequent production of a cylinder block, an aluminum alloy is cast around this surface, thus achieving a clinging effect between liner and base material. The structured surface of the lost mold can also be described as a particle layer permeated with holes on the inner mold of the lost core. An inventive layer differs from the generally common understanding of the word xe2x80x9clayerxe2x80x9d, however, in that cohesion is usually absent between the individual particles forming the layer and exists only between the inner core and the particles. The layer thickness is defined as the radial distance between the surface of the inner core and the extreme outer point of a particle.
The proportion of such holes, or in other words the surface not covered with particles, can have values ranging between 0% and 95% of the total area. Furthermore, it is also possible to provide the particles only locally, for example in an upper and a lower region of the inner core of the lost mold.
It is indeed known from EP 807479 A that a lost-foam core to be provided with a spray-metallized layer can be provided with an intermediate layer of a spray-resistant plastic such as polyamide and, during spraying of the polyamide layer, simultaneously there can be introduced metal particles, which remain as a structured metal layer during outgassing of the polyamide layer and are intended to improve the clinging of the spray-metallized layer to the material cast therearound, but this method is not comparable with the present method. In particular, during production of a corresponding layer by spraying, a good bond between the metal particles present in the intermediate layer and the spray-metallized layer can hardly be developed, since the difference between the melting points of the metal particles and plastic particles is too different.